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Passage One
学科分类: History
题目: The Classic Mayan Collapse
1. The classic Mayan collapse was caused by a combination of many factors, including natural disasters,diseases,agricultural depression,invasion from foreigners and internal chaos.
2. Earthquake and hurricane are two possible reasons. But they only occurred in central lowlands.There`s no historical record of earthquake in other parts of Mayan regions.
3. Drought is another hypothesis. A lake in that region had its driest period from A.D.800 to A.D.1000. Which is in classic period of Maya civilization But this lake is only a small part of Mayan region.
4. Agricultural depression also contributes to the collapse. They need large areas of land to grow crops, which led to the deforestation. Besides, they grew many kinds of crops at the beginning. But later, they only grew maize.
5. Increased population makes the food resources highly insufficient.Due to lack of food, they were very vulnerable to diseases and natural disasters.
6. Invasion from surrounding Mexican states is also a reason. And the change of trade pattern from inland to coast should also be taken into consideration. They followed the route of commerce and left their original home.
词汇题：
1. compounded=added to
2. accessible=available
3. consensus=widespread agreement
4. exclusive=sole
Passage Two
学科分类: Science
題目: The sleep
1. Though sleep creates dangers to animals and takes time away for doing things it serves important purpose: restoration, circadian rhythms and facilitation of learning.
2. During sleep,the body can rest and the bran can repair itself. Growth hormones only produced during sleep helps brain to regain its ability to fight disease.
3. The effects of sleep. A short period of deprivation of sleep has little influence on physical and cognitive performance. Two to three days of deprivation doesn't affect people`s strength, athletic ability and cognitive performance. But doing boring or ordinary things is impossible. Some brain scan revealed the activation of prefrontal cortex in short deprivation,which shows that brain can compensate for lack of sleep. But long deprivation of sleep generates greater i11uence on people's physical and cognitive performance. Experiment on rats showed that lack of sleep will do harm to immune system and eventually lead to death.
4. Sleep provides an opportunity for animals to be quite and inactive, keeping away from dangers which normally occurs in dark. Their wake-sleep cycle is consistent with light and dark. Though this has changed a little
5. Sleep is also a good way for animals to hide themselves. And the amount of time animals use to sleep is related to the time they seek food for survival. Small animals sleep more while large and vulnerable animals sleep less, like cows and deer. But large animals also sleep more like lions.
6. Sleep helps strengthen the ability to learn. During sleep, the nerve cells connection can be restored. Circuits wired together during the day will be consolidated and strengthened during sleep. Robert's research showed that at least six hour`s sleep helps participant improve tasks. Also,learning ability is strongly associated with change of nerve cells. Such change only happens during sleep. Infants and young kids tend to sleep the most because they learn great amount of thing in a short period of time.
词汇题：
1. indefinitely=endlessly
2. Compensate for=make up for
3. extended=lengthened
4. consistent=unvarying
Passage Three
学科分类: Biology
题目: The Qualities a Good Trout Streams
1. There are many trout streams in united States throughout the country. All the streams have some things in common.
2. Tout live in cool-to cold-water. But brown trout prefer warmer temperature from l0 tol6°C. In 2l°C,tout cannot compete with other fishes 23 to 26 is their lethal temperature.
3. Cover is important for a good tout steam. The examples include vegetation boulder under hanging banks branches. So good cover is necessary. Though tout is territorial.,so a tout tend to stay in the same pat, they prefer different cover according to their age and species. So a good trout stream must be abundant in all necessary covers.
4. Alternation of riffles. Gravel-bed stream is good for them to rest, hide and reproduce. They can take a station to rocks or obstructions, taking a foray to capture drifting prey.
5. Trout feed on capturing drifting insects and insects from bottom.So a good stream supports an abundant population of insects. They also eat small fish.
6. Small sand, rocks and places free of silts are good for their growth. We can also find trout in areas with sands and silts areas But these areas must have access to the palls of stream with gravel-bed, where they can construct redds and lay their eggs.
词汇题 ;
1. robust=healthy
2. optimal=ideal
3. obstruct1on=barrier
4. predominantly=mainly